Two-stroke internal combustion engine

ABSTRACT

In a two-stroke internal combustion engine with a crank slide mechanism and a plurality of working cylinders which, have bases and are divided by a piston into a lower and an upper cylinder chamber, the lower cylinder chamber being used substantially for compression and the upper cylinder chamber being used substantially for combustion, storage cylinders are provided which can be connected to cavities such as working cylinders of the engine and processing chambers such that each adjoining cavity has at least one closable inlet opening through which an air-fuel mixture, e.g. can flow from the storage cylinder into the cavity and at least one closable outlet opening through which the mixture can flow out of the cavity into the storage chamber. The storage chamber is charged by the lower cylinder chambers with the air-fuel mixture and the mixture is fed as necessary to the upper cylinder chambers for combustion or the mixture is conveyed out of the lower cylinder chambers into given compartments of the storage cylinder and from there is fed to the processing chambers for processing. After processing, the mixture is fed back to given compartments of the storage cylinder and then fed to the upper cylinder chambers for combustion. The storage cylinder enables circulation losses to be avoided since the air-fuel mixture is not introduced at bottom dead center of the pistons, rather during the compression stroke, e.g. when the outlet slot is closed.

BACKGROUND OF THE INVENTION

The invention concerns a two-stroke internal combustion enginecomprising a number of working cylinders having bases and subdivided viatheir pistons into a lower and an upper cylinder chamber, wherein thelower cylinder chamber functions substantially for compression and theupper cylinder chamber substantially for compression and combustion.

A two-stroke motor of this type has been proposed by the inventorGottfried Hillekum and has become known in the art from German PatentNo. 409919 of Feb. 16, 1925 entitled "Two-stroke Internal CombustionEngine with Two Oppositely Lying Cylinders".

Disadvantageously, this crank slide two-stroke internal combustionengine circulates the exhaust out of the working cylinder using a freshfuel-air mixture (fresh gas) when the piston moves through its bottomdead center position. Since, at this point of time, operation of theengine requires inlet and outlet openings to be simultaneously opened, aportion of the fresh gas unavoidably is circulated along with theexhaust. These circulation losses lead to increased fuel consumption, tohigh carbon monoxide and hydrocarbon concentrations in the exhaust gas,to increased particle formation, to charring and to wear.

It is therefore the underlying purpose of the present invention tofurther improve the conventional motor in such a fashion that itsdisadvantages are avoided.

SUMMARY OF THE INVENTION

In a first solution in accordance with the invention, the circulationlosses are avoided in that no circulation is performed. At the point intime at which the piston moves approximately in its bottom dead centerposition, the exhaust gas flows out through the outlet opening. At hightemperatures, the mass of exhaust gas which remains after closing theoutlet opening is small. Fresh gas subsequently brought in during thecompression stroke mixes with the remaining exhaust gas. Elimination ofthe circulation step leads to a well-dosed mixture of exhaust gas whichlowers nitrogen oxide emissions.

In a second solution in accordance with the invention, the circulationlosses are avoided in that circulation uses pure fresh air from anauxiliary compressor (e.g. an exhaust turbo compressor). At the point intime at which the piston moves at approximately its bottom dead centerposition, the exhaust gas is forced through the outlet opening. Theremaining circulation air, together with the fresh gas subsequentlyintroduced during the compression stroke, lead to a doubled reactive gasmass so that approximately twice the power can be expected. Even higherpower levels can be achieved if the auxiliary machine can be used as acharger. Utilization of the auxiliary machine as a circulator andcharger leads to better distribution of the auxiliary machine load sothat even engines having a low number of cylinders can profit from theadvantages of an auxiliary compressor.

The purpose in accordance with the invention is achieved with aplurality of novel construction and method features.

During the circulation process, conventional two-stroke engines mustbring the fresh gas into the working cylinder at the bottom dead centerposition of the piston within an amount of time which is in general muchtoo short. In contrast thereto, the motor in accordance with theinvention has the entire compression stroke. In this manner, circulationlosses are reduced to a minimum.

Charging during compression can, however, not be carried out by thelower cylinder chamber of the working cylinder, since the lower cylinderchamber is in a state of expansion. A prominent feature of the inventionconsists in having the lower cylinder chambers of other workingcylinders contribute to each charging of an upper cylinder chamber. Inprinciple, a working cylinder contributing to charging can be disposedat an opposite or adjacent position.

The engine in accordance with the invention is principally distinguishedin that at least one storage cylinder is provided for to which at leasttwo working cylinders are attached in such a fashion that at least oneinlet opening is provided for each attached working cylinder throughwhich a stream of fresh gas can flow from the storage cylinder into thecavity and each with at least one outlet opening through which a streamof fresh gas can flow out of the cavity into the storage cylinder.

The storage cylinder is preferentially fashioned as a hollow cylinderwhose longitudinal axis is parallel to the longitudinal axis of theattached working cylinders and which is occupied by a fresh gas slidingvalve in the form of a hollow cylinder borne in the storage cylinder ina displaceable fashion.

In this advantageous embodiment, the fresh gas sliding valve hasopenings corresponding to the inlet and outlet openings of the storagecylinder and the openings in the fresh gas sliding valve can bedisplaced over the openings in the storage cylinder in such a fashionthat the openings in the storage cylinder can be opened and closed viathe fresh gas sliding valve so that fresh gas can flow out of the lowercylinder chamber into the cavity of the fresh gas sliding valve or freshgas can flow out of the cavity of the fresh gas sliding valve into theupper cylinder chamber.

The fresh gas sliding valve is, in this advantageous embodiment, closedat its ends via lids.

The cavity of the fresh gas sliding valve can be subdivided with walls.These walls are necessary in the event that the fresh gas stored in thestorage cylinder is to be processed, with the processed gas not beingallowed to come into contact with the unprocessed gas. In this case, thestorage cylinder must have at least one inlet opening and at least oneoutlet opening connected to the processing chamber. Likewise the freshgas sliding valve must have additional corresponding openings.

In order to execute processing, the fresh gas is fed into a compartmentin the fresh gas sliding valve and passed from this location into aprocessing chamber or into a plurality of sequentially stackedprocessing chambers and, subsequent to processing, fed back to acompartment in the storage cylinder and introduced to the upper cylinderchamber.

It is advantageous in accordance with the invention to incorporate alltechnically possible and reasonable processing and improvements to thefresh gas stored in the storage cylinder in differing possibleprocessing chambers. One can provide that:

the processing chamber is a heat exchanger, e.g. an intermediatecharging air cooler by means of which heat can be extracted from thesystem,

the processing chamber is a heat exchanger by means of which heat can befed to the system, e.g. exhaust heat from processes, or heat from aconnected burner for sole hot air engine operation or combined hot airand combustion engine operation,

the processing chamber facilitates production of an emulsion fuelthrough the addition of water or steam and through the addition of anemulsifying agent,

the processing chamber has a filter,

the processing chamber has a catalytic converter,

the processing chamber is a reactor with the assistance of which andwith the addition of reactive materials, an improvement in the qualityof the exhaust or a reduction in the emission of pollutants is effected,

the processing chamber facilitates a combination of the above-mentionedpossibilities or effects processing not mentioned herein.

In an advantageous embodiment of the invention, movement of the freshgas sliding valve is coupled to motion of the pistons and drivendirectly or indirectly by means of a crank shaft cam.

It is also possible for the fresh gas sliding valve to be configured insuch a fashion that the separation from the crank shaft is adjustable sothat the opening and closing of the storage chamber openings can bedisplaced relative to the motion of the piston.

Various constructive features should be mentioned with regard to thenumber of working cylinders:

In an embodiment having two working cylinders, the pneumatic cooperationtakes place between oppositely lying working cylinders. In order to beable to guide the fresh gas from one working cylinder to the oppositelylying working cylinder, the cavity of the fresh gas sliding valve musttraverse the crank case. This is possible when the crank shaft isdisposed in a sidewardly displaced fashion and if the device forconnecting the piston rods and the fresh gas sliding valve to the crankshaft is sidewardly disposed.

In an embodiment having an number of working cylinders which is amultiple of four, the pneumatic cooperation preferentially occursbetween two neighbouring working cylinders whose input and outputopenings are connected to the storage cylinder. Two oppositely lyingfresh gas sliding valves can be unified into a fresh gas sliding valveunit. In this fashion, one crank shaft cam can operate four workingcylinders.

An embodiment of the invention provides that, in addition to theopenings for the storage cylinder, the working cylinders have openingsfor fresh air or for fresh gas input channels and for circulating airand outlet channels for exhaust gas, which can be closed via additionalcontrol valves with these control valves being directly or indirectlydriven by a cam on the crank shaft. In this fashion one guarantees thatall control functions on the motor are performed via the crank shaft,same being, in any event, necessary for power transmission.

The circulation air inlet openings can be closed along with the exhaustgas opening via a common control valve (circulation air exhaust gassliding valve). In this fashion only one sliding valve is required forthe circulation air inlet and the exhaust gas outlet.

One part of the circulation air channel can be eliminated in the eventthat the cavity in which the sliding valve moves, forms a part of thecirculation air channel.

In addition, openings are provided for equilibration of pressuredifferences between the circulation air channel and the workingcylinder.

Additional advantages can be derived from the description of theaccompanying drawing. The above mentioned features and those describedbelow can be utilized in accordance with the invention individually orcollectively in arbitrary combination. The embodiments shown are not tobe considered as exhaustive enumeration, rather have exemplarycharacter.

An embodiment of the invention is represented in the drawing and will bemore closely described below. This embodiment concerns a four cylinderengine which is partially shown in a highly schematic fashion and is notto be taken to scale.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a plan view of an exemplary embodiment of the internalcombustion engine in accordance with the invention.

FIG. 2 shows a cross-section through an exemplary embodiment of theinternal combustion engine in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As seen in FIG. 1, working cylinders 11 and 12 are disposed in acylinder housing, within which pistons 13 and 14 can be moved back andforth. The pistons 13 and 14 are connected to crank links 17 and 18 bymeans of piston rods 15 and 16. Link blocks 19 and 20 are disposed in amovable fashion in the crank links 17 and 18 and can be driven by meansof the pistons 13 and 14 and the crank links 17 and 18. The link blocks19 and 20 direct the force onto crank pins (not shown) of the crankshaft 23. A mechanical configuration of this type is e.g. realized inthe Hellekum motor (inventor Gottfried Hellekum).

During the first bottom dead center position of pistons 13 and 14, thefresh gas sliding valve 27 assumes a middle position. In this locationopenings 30, 31, 32 and 33 of the storage chamber 28 are sealed by thefresh gas sliding valve 27. After ignition of the spark plug 26, thepiston 13 proceeds through the first half-stroke in the downwarddirection and the piston 14 through its first half-stroke in the upperdirection. The fresh gas sliding valve 27 moves by a half stroke in theupper direction to open the inlet opening 30 of the storage cavity 28.In this fashion the air fuel mixture contained in the lower cylinderchamber of the working cylinder 11 can escape into the storage chamber28.

The role of the chamber in a two stroke engine in accordance with theinvention is thereby simplified in that as many working cylinders areconnected which operate in the same sense as working cylinders operatingin an opposing sense. In this manner the volume introduced fromconnected working cylinders operating in the same sense is approximatelythe same as the volume removed from those working in an opposite sense.In this fashion pressure variations in the storage unit are avoided. Theworking cylinder 12 belongs to the group of working cylinders operatingin an opposing sense relative to the working cylinder 11.

The working cylinder 12 now requires input of air-fuel mixture into itsupper cylinder chamber. This requirement is satisfied by the storagechamber 28. Motion of the fresh gas sliding valve 27 by a half a strokein the upper direction causes the outlet opening 31 of the storagechamber 28 to also open so that the air-fuel mixture can flow out of thestorage unit 28 into the upper cylinder chamber of the working cylinder12. During the time in which the piston exercises its second strokehalf, the fresh gas sliding valve 27 moves downwards by a half a strokeback into its intermediate position.

In the second dead center location of the pistons 13 and 14, theopenings 30, 31, 32, 33 of the storage chamber 28 are sealed by thefresh gas sliding valve 27. After ignition of the spark plug 34, thepiston 14 exercises the first half stroke in the downward direction andthe piston 13 the first half stroke in the upper direction. The freshgas sliding valve 27 moves by a half stroke in the downward directionand opens the inlet opening 33 of the storage chamber 28. In this mannerthe air fuel mixture contained in the lower cylinder chamber of workingcylinder 12 can escape into the storage chamber 28.

At this point the working cylinder 11 requires air-fuel mixture inputinto its upper cylinder chamber. This requirement is satisfied by thestorage chamber 28. By means of the motion of the fresh gas slidingvalve 27 by half of a stroke in the downward direction, the outletopening 32 of the storage chamber 28 is also opened so that the air-fuelmixture can flow out of the storage unit 28 into the upper cylinderchamber of the working cylinder 11.

During the time at which the piston exercises its second stroke half,the fresh gas sliding valve 27 moves back by a half a stroke in theupward direction into its middle position to thereby close the inletopening 33 and the outlet opening 32 of the storage chamber 28. At thispoint the initial position is regained.

The working cylinders 11 and 12, having spark plugs 26 and 34, aredisposed directly opposite to working cylinders 41 and 42. Pistons 43and 44 of working cylinders 41 and 42 are connected to crank links 17and 18 via common piston rods 15 and 16. Motion of the piston 43 isthereby coupled to motion of the piston 13, whereas the motion of thepiston 44 is coupled to the motion of the piston 14. The storage chamber48, having the fresh gas sliding valve 47 and openings 51, 52, 53 and50, is located across from the storage chamber 28 having the fresh gassliding valve 27 and the openings 30, 31, 32 and 33. Motion of the freshgas sliding valve 47 is coupled to motion of the fresh gas sliding valve27.

As seen in FIG. 2, in working cylinders 60 and 90, the fresh air inletchannels 61 and 81 are controlled by suction valves and the exhaustoutlet channels 62 and 82 as well as the circulation air inlet channels63 and 83 are controlled by the fresh air exhaust sliding valves 65 and85 which are connected to crank link 66. The connection to the cranklink couples the circulation air exhaust gas sliding valves 65 and 85 tothe motion of the pistons 67 and 87 and thereby to motion of the crankshaft 92. A free end of the exhaust gas-fresh air sliding valves 65 and85 opens and closes the circulation air inlet channels 63 and 83. Thechannel through holes 71 and 91 of the circulation air exhaust gassliding valves 65 and 85 overlap with the exhaust gas outlet channels 62and 82 so that the exhaust gas can escape together with the blown incirculation air approximately at the bottom dead center position of thepistons 67 and 68. Through holes 68 and 88 provide for reduction of highpressure of the trapped exhaust gas in the channel through holes 71 and91 after passage through openings 68 and 89 during motion of thecirculation air exhaust gas sliding valves 65 and 85 in the downwarddirection.

I claim:
 1. A two-stroke internal combustion engine comprising pairs ofcylinders aligned opposite to each other separated by a crank case, eachpair of cylinders having a common piston rod to transmit a power outputof said engine, the engine comprising:a crank shaft disposed in thecrank case; a first cylinder having a head at one end and a base at anopposite end, said base having a hole, said first cylinder also having afirst piston subdividing said first cylinder into an upper chamberadjacent to said head and lower chamber adjacent to said base, saidlower chamber for charging during an upward motion of said piston andfor compression during a downward motion of said first piston, saidupper chamber for compression during an upward motion of said firstpiston and for power production during a downward motion of said firstpiston, said first cylinder also having a first piston rod passingthrough said hole in said base, connected between said first piston andsaid crank shaft, and disposed largely transverse to said crank shaftfor rotating said crank shaft during a downward motion of said firstpiston, said first cylinder having an inlet opening proximate to saidhead and an outlet opening proximate to said base; a second cylinderhaving a head at one end and a base at an opposite end, said base havinga hole and also having a second piston subdividing said second cylinderinto an upper chamber adjacent to said head and a lower chamber adjacentto said base, said lower chamber for charging during an upward motion ofsaid second piston and for compression during a downward motion of saidsecond piston, said upper chamber for compression during an upwardmotion of said second piston and for power production during a downwardmotion of said second piston, said second cylinder also having a secondpiston rod passing through said hole in said base, connected betweensaid second piston and said crank shaft and disposed largely transverseto said crank shaft for rotating said crank shaft during a downwardmotion of said second piston, said second cylinder having an inletopening proximate to said head and an outlet opening proximate to saidbase, wherein said second piston is proximate to said base of saidsecond cylinder when said first piston is proximate to said head of saidfirst cylinder and wherein said second piston is proximate to said headof said second cylinder when said first piston is proximate to said baseof said first cylinder; and a storage chamber parallel to and connectedbetween said first and said second cylinders, said storage chamberhaving a sliding valve displaceable in a direction parallel to alongitudinal axis of said first and said second cylinders inside saidstorage chamber, said sliding valve having openings communicating withsaid inlet and outlet openings in said first and said second cylindersto connect said upper and said lower chambers of said first and saidsecond cylinders to said storage chamber.
 2. The engine of claim 1,wherein said storage chamber is subdivided into a plurality of stackedstorage chambers.
 3. The engine of claim 1, wherein said sliding valveis closed at its ends.
 4. The engine of claim 1, wherein said slidingvalve has a cavity divided by walls.
 5. The engine of claim 1, furthercomprising means for coupling a motion of said sliding valve to a motionof said first and said second pistons.
 6. The engine of claim 5, furthercomprising means for coupling a motion of said sliding valve to a motionof said crank shaft.
 7. The engine of claim 6, wherein said means forcoupling said sliding valve to said crank shaft is adjustable relativeto a separation between said crank shaft and said sliding valve.
 8. Theengine of claim 1, wherein said first cylinder is aligned opposite tosaid second cylinder and said first and second cylinders are separatedby the crank case and said sliding valve traverses said crank case, saidsliding valve having an undivided cavity.
 9. The engine of claim 6,further comprising a second sliding valve connected to said firstsliding valve to form a sliding valve unit driven by said crank shaft.10. The engine of claim 1, wherein said openings in said sliding valveand a displacement of said sliding valve first open and then close saidoutlet opening of said first cylinder together with said inlet openingof said second cylinder to push compressed gas out of the said firstcylinder into a cavity of said sliding valve and then into said secondworking cylinder, and thereafter first open and then close said outletopening of said second working cylinder together with said inlet openingof said first working cylinder to push compressed gas out of said secondcylinder into said cavity of said control valve and then into said firstcylinder.
 11. The engine of claim 1, wherein said sliding valve has apartition directed transverse to a longitudinal axis of said slidingvalve to subdivide a cavity of said sliding valve for directing a flowof gas to a processing chamber disposed within a gas path between saidfirst and said second cylinders.
 12. The engine of claim 1, wherein saidfirst and said second cylinders have additional inlet openings for atleast one of fresh air, an air-fuel mixture, and circulation air andadditional outlet channels for exhaust gas, said additional openings andsaid additional outlet channels sealed by additional sliding valvesdriven by said crank shaft.
 13. The engine of claim 12, wherein saidfirst and said second cylinders have an additional inlet opening forcirculation air, and said circulation air inlet opening and said exhaustgas outlet channel for sealing by a common circulation air exhaust gassliding valve.
 14. The engine of claim 13, wherein said circulation airexhaust gas sliding valve has a cavity forming part of a circulation airchannel.
 15. The engine of claim 14, wherein said circulation airexhaust gas sliding valve cavity has openings for connection to saidfirst and said second cylinders.
 16. The engine of claim 1, furthercomprising an auxiliary compressor for circulation of said first andsaid second cylinder upper chambers and for charging said first and saidsecond cylinder lower chambers.
 17. The engine of claim 1, furthercomprising an additional engine chamber connectable to said storagechamber, wherein said storage chamber has an additional inlet openingthrough which gas can flow from said additional chamber into saidstorage chamber, and said storage chamber has an additional outletopening through which gas can flow out of said storage chamber into saidadditional chamber.